In a gear transmission apparatus for an automobile, an input shaft is, at a rear portion thereof, provided with an input gear that meshes with a counter gear on the counter shaft located below the input shaft. An output shaft is, at a front portion thereof, fitted to and supported by the rear portion of the input shaft by a bearing unit (a so-called pilot bearing). The bearing unit allows the relative rotation during the non direct drive mode of the transmission wherein the rotation of the input shaft is transmitted to the output shaft via the counter shaft under predetermined gear ratios.
In the conventional transmission apparatus, the lubricant oil is supplied to the pilot bearing via oil holes formed in the input gear so that they are opened to bottom portions of spaces formed between adjacent teeth of the input gear. The lubricant oil is, under the force generated between the input gear and the counter gear meshing with each other, urged into the oil holes. Thus, the lubrication of the pilot bearing is effected by the oil from the oil holes.
However, prior art suffers from the drawback that an amount of oil sufficient for effectively lubricating the pilot bearing is not directed to the oil holes. This is especially true when gears of small pitch are utilized in order to decrease the operational noise generated by the gears, since the formation of oil holes of large diameter is difficult due to the small distance between the adjacent teeth of the input gear.